Python Api to connect to Utility network

[Rahul_Pandia]

Hello,
 I want to update Utility network's feature class attributes for example "Notes columns".
Error :

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Exception                                 Traceback (most recent call last)
In  [121]:
Line 1:     update_result = layer.edit_features(updates=[sfo_edit])

File E:\Shared_fold\arcgispro-py3-cloneUN\Lib\site-packages\arcgis\features\layer.py, in edit_features:
Line 2827:  return self._con.post_multipart(path=edit_url, postdata=params)

File E:\Shared_fold\arcgispro-py3-cloneUN\Lib\site-packages\arcgis\gis\_impl\_con\_connection.py, in post_multipart:
Line 868:   force_bytes=kwargs.pop("force_bytes", False),

File E:\Shared_fold\arcgispro-py3-cloneUN\Lib\site-packages\arcgis\gis\_impl\_con\_connection.py, in _handle_response:
Line 625:   self._handle_json_error(data["error"], errorcode)

File E:\Shared_fold\arcgispro-py3-cloneUN\Lib\site-packages\arcgis\gis\_impl\_con\_connection.py, in _handle_json_error:
Line 648:   raise Exception(errormessage)

Exception: Unable to complete operation.
Features that are utility network subnetwork controllers do not support edits to asset group or asset type attributes.
(Error Code: 400)
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My code is :

from arcgis.features import FeatureLayer
lyr_url = 'https://abc.test1.com/server/rest/services/BCMCSJ3_5/FeatureServer/0'

layer = FeatureLayer(lyr_url)
ports_fset = layer.query()
ports_features = ports_fset.features
sfo_feature = [f for f in ports_features if f.attributes['OBJECTID']==3][0]
sfo_edit = sfo_feature
sfo_edit.attributes['NOTES2'] = 'RPN'
update_result = layer.edit_features(updates=[sfo_edit])